JP6264167B2 - Control device - Google Patents

Description

  The present invention relates to a control device, and more particularly to a control device that controls an ignition device of an internal combustion engine.

  Conventionally, a control device that controls an ignition device of an internal combustion engine and controls ignition of an air-fuel mixture in a combustion chamber is known. For example, in the control device described in Patent Document 1, the combustion state of the air-fuel mixture in the combustion chamber is estimated based on a signal from a pressure sensor that detects the pressure in the combustion chamber, and the ignition timing or the like is determined according to the estimated combustion state. Control is performed.

Japanese Utility Model Publication No. 62-59772

  However, in the case of the control device of Patent Document 1, it is necessary to provide a pressure sensor in the combustion chamber in order to estimate the combustion state of the fuel in the combustion chamber. Therefore, the cost may increase. Further, when the pressure sensor fails, there is a possibility that the combustion state cannot be estimated.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a control device capable of estimating the combustion state of the air-fuel mixture in the combustion chamber with a simple configuration.

  The present invention controls an ignition device including an ignition plug, an ignition coil, an igniter unit, and an energy input unit, and can control ignition of an air-fuel mixture in a combustion chamber of an internal combustion engine. Means and combustion state estimating means. Here, the spark plug is provided in the combustion chamber of the internal combustion engine, and can ignite the air-fuel mixture in the combustion chamber by discharging. The ignition coil has a primary coil having one end connected to the power supply side and the other end connected to the ground side, and a secondary coil having one end connected to the spark plug. The igniter portion is provided so as to allow or block the flow of current from the primary coil to the ground side. The energy input unit can input electric energy to the ignition coil.

The control unit includes discharge control means, energy input control means, normal ignition control means, and specific ignition control means, and can control ignition of the air-fuel mixture in the combustion chamber.
The discharge control means controls the ignition plug so that a high voltage is generated in the secondary coil by controlling the igniter so as to cut off the flow of current from the primary coil to the ground side, and the ignition plug is discharged. Thereby, the spark plug is discharged, and the air-fuel mixture can be ignited.

The energy input control unit controls the energy input unit so as to input electric energy to the ignition coil after the ignition control control is started by the discharge control unit. Thereby, the discharge state of the spark plug generated by the control of the discharge control means can be maintained. Therefore, the ignitability of the air-fuel mixture can be improved.
The normal ignition control means controls ignition of the air-fuel mixture in the combustion chamber only by controlling the spark plug by the discharge control means.
The specific ignition control unit controls ignition of the air-fuel mixture in the combustion chamber by controlling the spark plug by the discharge control unit and controlling the energy input unit by the energy input control unit.
The voltage detection means can detect the voltage between the secondary coil and the spark plug.

  In the combustion stroke of the internal combustion engine, the combustion state estimation means controls the ignition plug by the discharge control means after “ignition control by the normal ignition control means” or “ignition control by the specific ignition control means”, and energy input control The energy input unit is controlled by the means, and the combustion state of the air-fuel mixture in the combustion chamber can be estimated based on the voltage value corresponding to the voltage detected by the voltage detection means.

  Thus, in the present invention, in order to estimate the combustion state of the air-fuel mixture in the combustion chamber, it is not necessary to provide pressure detection means such as a pressure sensor in the combustion chamber. Therefore, the combustion state can be estimated with a simple configuration, and the cost can be reduced. Further, since there is no need to provide pressure detection means such as a pressure sensor in the combustion chamber, a situation such as “the combustion state cannot be estimated due to failure of the pressure detection means” is not caused.

The figure which shows the control apparatus by one Embodiment of this invention, and the engine system to which this is applied. The figure which shows the circuit structure of the control apparatus by one Embodiment of this invention. The figure for demonstrating the operation example of the control apparatus and ignition device of one Embodiment of this invention. The figure for demonstrating the method of estimation of the combustion pressure and combustion speed by the control apparatus of one Embodiment of this invention. The figure which shows the relationship between the cylinder internal pressure and crank angle in the combustion stroke of the engine of the engine system to which the control apparatus by one Embodiment of this invention is applied. The figure for demonstrating the method of the estimation of a combustion state by the control apparatus of one Embodiment of this invention.

Hereinafter, a control device according to an embodiment of the present invention will be described with reference to the drawings.
(One embodiment)
A control device according to an embodiment of the present invention is shown in FIGS. The control device 10 is applied to the engine system 1 and can control each unit constituting the engine system 1.

The engine system 1 includes an engine 20 as an internal combustion engine, an ignition device 11 and the like.
The engine 20 is a premixed combustion type four-cylinder engine driven by, for example, gasoline as fuel. The engine 20 includes a cylinder 21, an engine head 22, an intake valve 25, an exhaust valve 26, a piston 27, a crankshaft 29, and the like.

The cylinder 21 is formed in a cylindrical shape. In the present embodiment, four cylinders 21 are formed in the engine 20. The engine head 22 is provided so as to close one end of the cylinder 21. The engine head 22 is formed with an intake port 23 and an exhaust port 24 that communicate with the inner space of the cylinder 21.
The intake valve 25 is provided so as to be able to open and close between the intake port 23 and the inner space of the cylinder 21. The exhaust valve 26 is provided so as to be able to open and close between the exhaust port 24 and the inner space of the cylinder 21.

  The piston 27 is provided so as to reciprocate in the axial direction inside the cylinder 21. A combustion chamber 28 is formed by the inner wall of the cylinder 21, the engine head 22, and the piston 27. When the gas in which fuel and air are mixed, that is, the air-fuel mixture burns in the combustion chamber 28, the volume of the combustion chamber 28 increases and the piston 27 moves to the side opposite to the engine head 22. When the air-fuel mixture burns in the combustion chamber 28, combustion gas is generated.

  The crankshaft 29 is rotatably provided by the reciprocating movement of the piston 27. When fuel burns in the combustion chamber 28 and the piston 27 reciprocates in the cylinder 21, the crankshaft 29 rotates and torque is output from the crankshaft 29. Torque output from the crankshaft 29 is transmitted to a vehicle wheel (not shown). Thereby, the vehicle travels.

  An intake pipe 31 is connected to the intake port 23 of the engine head 22. An intake passage 32 is formed inside the intake pipe 31. One end of the intake passage 32 is open to the atmosphere, and the other end is connected to the intake port 23. Thus, the atmosphere (air) is supplied to the combustion chamber 28 via the intake passage 32 and the intake port 23. Hereinafter, air supplied from the atmosphere side to the combustion chamber 28 of the engine 20 will be referred to as intake air.

  A throttle valve 2 is provided in the intake passage 32. The throttle valve 2 can be opened and closed by being driven to rotate by the actuator 3. That is, the throttle valve 2 can change the amount of intake air supplied to the combustion chamber 28 by opening and closing the intake passage 32.

  A fuel injection valve 4 is provided in the vicinity of the engine head 22 of the intake pipe 31. The fuel injection valve 4 can inject fuel into the intake port 23. As a result, an air-fuel mixture of fuel and intake air (air) is supplied to the combustion chamber 28. The fuel injection valve 4 can change the amount of fuel to be injected by controlling the opening and closing of the injection hole. That is, the fuel injection valve 4 can change the amount of fuel supplied to the combustion chamber 28.

  An exhaust pipe 33 is connected to the exhaust port 24 of the engine head 22. An exhaust passage 34 is formed inside the exhaust pipe 33. The exhaust passage 34 has one end connected to the exhaust port 24 and the other end open to the atmosphere. Thereby, the air containing the combustion gas generated in the combustion chamber 28 is discharged to the atmosphere side through the exhaust port 24 and the exhaust passage 34. Hereinafter, the air containing the combustion gas discharged from the combustion chamber 28 of the engine 20 is referred to as exhaust as appropriate. In the present embodiment, a three-way catalyst 35 is provided in the exhaust passage 34. The three-way catalyst 35 purifies the exhaust discharged to the atmosphere side by oxidizing or reducing hydrocarbons, carbon monoxide, and nitrogen oxides in the exhaust.

  In the present embodiment, the engine system 1 includes an EGR pipe 36 that connects the intake pipe 31 and the exhaust pipe 33. An EGR passage 37 is formed inside the EGR pipe 36. The EGR passage 37 communicates the exhaust passage 34 and the intake passage 32. As a result, the exhaust in the exhaust passage 34 can be recirculated to the intake passage 32 via the EGR passage 37.

  An EGR valve device 5 is provided in the EGR pipe 36. The EGR valve device 5 can open and close the EGR passage 37 by an EGR valve (not shown). That is, the EGR valve device 5 can change the amount of exhaust gas recirculated from the exhaust passage 34 to the intake passage 32 by opening and closing the EGR passage 37.

Here, the EGR pipe 36 and the EGR valve device 5 constitute an exhaust gas recirculation (EGR) system that supplies exhaust gas discharged from the combustion chamber 28 of the engine 20 to the combustion chamber 28 together with intake air. . By supplying the exhaust gas to the combustion chamber 28 together with the intake air, it is possible to reduce nitrogen oxides in the exhaust gas exhausted to the atmosphere, improve the fuel consumption, and the like.
The ignition device 11 is provided for igniting the air-fuel mixture introduced into the combustion chamber 28. As shown in FIG. 2, the ignition device 11 includes a spark plug 40, an ignition coil 50, an igniter section 60, an energy input section 70, and the like.

  Four spark plugs 40 are provided so as to correspond to each of the four cylinders 21. The spark plug 40 has a discharge part 41. The discharge part 41 has a center electrode 42 and a ground electrode 43. A predetermined gap is formed between the center electrode 42 and the ground electrode 43. The spark plug 40 is provided in the engine head 22 so that the discharge part 41 is exposed to the combustion chamber 28 (see FIG. 1). The ground electrode 43 is electrically connected to the engine head 22. That is, the ground electrode 43 is grounded. The spark plug 40 discharges between the center electrode 42 of the discharge part 41 and the ground electrode 43 by the applied voltage, and can ignite the air-fuel mixture in the combustion chamber 28.

  Four ignition coils 50 are provided so as to correspond to each of the four spark plugs 40 (cylinders 21). The ignition coil 50 is provided on the engine head 22 so that one end thereof is connected to the side opposite to the discharge part 41 of the spark plug 40 (see FIG. 1). The ignition coil 50 has a primary coil 51, a secondary coil 52, a core 53, and a diode 54 (see FIG. 2).

  The primary coil 51 is formed by winding a copper wire around the core 53 a predetermined number of times, for example, and one end is connected to the positive electrode of the power source 12. The power source 12 is a low-voltage battery that can output a voltage of about ten and several volts from the positive electrode, and the negative electrode is grounded (body earth). The other end of the primary coil 51 is grounded.

The secondary coil 52 is formed, for example, by winding a copper wire around the core 53 a predetermined number of times, and one end is connected to the center electrode 42 of the spark plug 40 and the other end is grounded. Here, the number of turns of the secondary coil 52 is set to be larger than that of the primary coil 51.
The core 53 is made of a material having a magnetic permeability of a predetermined value or more, such as iron.

  The diode 54 is provided on the side opposite to the spark plug 40 with respect to the secondary coil 52. The diode 54 is provided such that the anode side is connected to the secondary coil 52 and the cathode side is grounded. As a result, a current flow from the secondary coil 52 to the ground side via the diode 54 is allowed, and a current flow from the ground side to the secondary coil 52 side via the diode 54 is blocked.

  Four igniter portions 60 are provided so as to correspond to each of the four ignition coils 50 (cylinders 21). The igniter section 60 is provided on the opposite side of the power supply 12 with respect to the primary coil 51 of the ignition coil 50 (see FIG. 2). The igniter unit 60 includes a switching element 61 and a diode 62.

  In the present embodiment, the switching element 61 is, for example, an IGBT (Insulated Gate Bipolar Transistor). The switching element 61 is provided such that the collector is connected to the primary coil 51 and the emitter is grounded. The switching element 61 performs a switching operation based on a signal input to the gate so that the switching element 61 is turned on or off. The switching element 61 allows a current flow from the primary coil 51 to the ground side via the switching element 61 when in the on state, and from the primary coil 51 to the ground side via the switching element 61 when in the off state. Cut off current flow.

  The diode 62 has an anode connected to the emitter of the switching element 61, that is, grounded. The diode 62 is connected to the collector of the switching element 61 on the cathode side, that is, to the primary coil 51. Thereby, the flow of current from the ground side to the primary coil 51 side via the diode 62 is allowed, and the current flow from the primary coil 51 side to the ground side via the diode 62 is blocked.

  When the switching element 61 of the igniter unit 60 is in the on state, the current from the power source 12 flows to the ground side via the primary coil 51 and the switching element 61 of the ignition coil 50. At this time, the core 53 is magnetized to store magnetic energy, and a magnetic field is formed around it. When the current flows through the primary coil 51 and the switching element 61 is turned off, the current flow from the primary coil 51 to the ground side is cut off, the magnetic field around the core 53 changes, and the primary induction occurs due to the self-induction action. A voltage of about several hundred volts is generated in the coil 51. At this time, a high voltage of about several tens of kV is also generated in the secondary coil 52 sharing the magnetic circuit and the magnetic flux. At this time, the voltage generated in the secondary coil 52 has a magnitude proportional to the number of turns of the primary coil 51 and the secondary coil 52. When a high voltage is generated in the secondary coil 52, the potential difference between the center electrode 42 of the spark plug 40 and the ground electrode 43 becomes a predetermined value or more. As a result, dielectric breakdown occurs between the center electrode 42 and the ground electrode 43, and the spark plug 40 discharges between the center electrode 42 and the ground electrode 43.

Hereinafter, as appropriate, the current flowing through the primary coil 51 is referred to as a primary current I1, the current flowing through the secondary coil 52 is referred to as a secondary current I2, and the voltage of the secondary coil 52 is referred to as a secondary voltage V2. The direction from the power supply 12 side to the igniter 60 side is the positive direction of the primary current I1, and the direction from the diode 54 side to the spark plug 40 side is the positive direction of the secondary current I2. Further, the secondary voltage V2 when the secondary current I2 in the positive direction flows through the secondary coil 52 is a positive voltage.
In the present embodiment, when the spark plug 40 is discharged, the secondary voltage V2 is a negative voltage, and a secondary current I2 in the negative direction flows through the secondary coil 52.

In the present embodiment, one energy input unit 70 is provided for the four ignition coils 50. The energy input unit 70 is provided in parallel with the primary coil 51 between the power supply 12 and the igniter unit 60 (see FIG. 2). The energy input unit 70 includes a coil 71, switching elements 72 and 73, diodes 74 and 75, a capacitor 76, and driver circuits 77 and 78.
The coil 71 is formed, for example, by winding a copper wire a predetermined number of times, and one end thereof is provided so as to be connected between the power supply 12 and the primary coil 51.

  In the present embodiment, the switching elements 72 and 73 are a kind of field effect transistor MOSFET (metal-oxide-semiconductor field-effect transistor). The switching element 72 is provided such that the drain is connected to the other end of the coil 71 and the source is grounded. The switching element 73 is provided such that its drain is connected between the coil 71 and the switching element 72 and its source is connected between the primary coil 51 and the igniter section 60 of the ignition coil 50. In the present embodiment, four switching elements 73 are provided corresponding to each of the four ignition coils 50 (cylinders 21).

  The switching elements 72 and 73 perform a switching operation based on a signal input to the gate so that the switching elements 72 and 73 are turned on or off. When the switching element 72 is in the on state, the switching element 72 allows a current to flow from the coil 71 to the ground side via the switching element 72. When the switching element 72 is in the off state, the current flows from the coil 71 to the ground side via the switching element 72. Cut off the flow. When the switching element 73 is in the on state, the current flow from the coil 71 and the switching element 72 side to the primary coil 51 and the igniter unit 60 side via the switching element 73 is allowed. The flow of current from the element 72 side to the primary coil 51 and the igniter unit 60 side via the switching element 73 is interrupted.

  The diode 74 is provided so that the anode side is connected between the coil 71 and the switching element 72 and the cathode side is connected to the drain of the switching element 73. Thereby, the flow of current from the coil 71 and the switching element 72 side to the switching element 73 side via the diode 74 is allowed, and the current flowing from the switching element 73 side to the coil 71 and switching element 72 side via the diode 74 is allowed. The flow is interrupted.

The diode 75 is provided such that the anode side is connected to the source of the switching element 73 and the cathode side is connected between the primary coil 51 and the igniter unit 60. Thereby, the flow of current from the switching element 73 side to the primary coil 51 and the igniter section 60 side via the diode 75 is allowed, and from the primary coil 51 and igniter section 60 side to the switching element 73 side via the diode 75. Current flow is interrupted. In the present embodiment, four diodes 75 are provided corresponding to each of the four switching elements 73.
The capacitor 76 is provided so that one end is connected between the diode 74 and the switching element 73 and the other end is grounded.

  The driver circuit 77 generates a switching signal SWc related to the switching operation of the switching element 72 based on the input signal, and outputs the generated switching signal SWc to the gate of the switching element 72. Here, the switching signal SWc is a signal indicating OFF (Lo) or ON (Hi). When the switching signal SWc is off, the switching element 72 is turned off, and when the switching signal SWc is on, the switching element 72 is turned on. As described above, the switching element 72 performs a switching operation based on the switching signal SWc input from the driver circuit 77.

  The driver circuit 78 generates a switching signal SWd related to the switching operation of the switching element 73 based on the input signal, and outputs the generated switching signal SWd to the gate of the switching element 73. Here, the switching signal SWd is a signal indicating OFF (Lo) or ON (Hi). When the switching signal SWd is off, the switching element 73 is turned off, and when the switching signal SWd is on, the switching element 73 is turned on. As described above, the switching element 73 performs a switching operation based on the switching signal SWd input from the driver circuit 78. In the present embodiment, four driver circuits 78 are provided corresponding to each of the four switching elements 73, but the present invention is not limited to this.

When the switching element 73 is off and the switching element 72 is on, the current from the power source 12 flows to the ground side via the coil 71 and the switching element 72. At this time, electrical energy is stored in the coil 71. When the current flows through the coil 71, if the switching element 72 is turned off, the current flow from the coil 71 to the ground side is interrupted. As a result, electric energy is released from the coil 71 and supplied to the capacitor 76 via the diode 74. Therefore, when the switching operation is performed so that the switching element 73 is turned off and the switching element 72 is repeatedly turned on or off alternately, electric energy is gradually accumulated from the coil 71 to the capacitor 76. At this time, the voltage Vdc at one end of the capacitor 76 gradually increases. When the electric energy is stored in the capacitor 76, and when the switching element 61 of the igniter unit 60 is turned off and the switching element 73 is turned on, the electric energy of the capacitor 76 passes through the switching element 73 and the diode 75. , Is supplied (input) to the primary coil 51 of the corresponding ignition coil 50. As described above, the energy input unit 70 can store the electric energy from the power source 12 in the capacitor 76 and can input it to the ignition coil 50. In the present embodiment, the energy input unit 70 ignites so that the secondary current I2 having the same polarity as the secondary current I2 flowing through the secondary coil 52 when the spark plug 40 is discharged, that is, the secondary current I2 in the negative direction is superimposed. Electric energy is input to the coil 50.
In the present embodiment, the igniter unit 60 and the energy input unit 70 described above are accommodated in the casing of the ignition circuit unit 13 (see FIG. 2).

As shown in FIG. 2, the control device 10 includes a control unit 81, a current detection circuit 91, a voltage detection circuit 95, and the like.
In the present embodiment, the control unit 81 is housed in a housing of an electronic control unit (hereinafter referred to as “ECU”) 80.
The control unit 81 is, for example, a microcomputer, and includes a CPU as arithmetic means, a ROM and RAM as storage means, a timer as time measurement means, I / O as input / output means, and the like. The control unit 81 performs operations according to a program stored in the ROM based on signals from sensors provided in each part of the vehicle, and controls the operation of devices and devices in each part of the vehicle, thereby integrating the vehicle. Can be controlled.

  As shown in FIG. 1, in this embodiment, a throttle opening sensor 6 is provided in the vicinity of the throttle valve 2 of the intake pipe 31. The throttle opening sensor 6 detects the opening of the throttle valve 2 in the intake passage 32 and outputs a signal correlated with the detected opening to the control unit 81. Thereby, the control part 81 can detect the opening degree of the throttle valve 2.

  An air flow meter 7 is provided on the side opposite to the engine 20 with respect to the throttle valve 2 of the intake pipe 31. The air flow meter 7 detects the amount of intake air flowing through the intake passage 32, that is, the amount of intake air supplied to the combustion chamber 28 of the engine 20, and outputs a signal correlated to the detected amount of intake air to the control unit 81. Thus, the control unit 81 can detect the amount of intake air supplied to the combustion chamber 28.

  An intake pressure sensor 8 is provided in a surge tank between the throttle valve 2 of the intake pipe 31 and the engine 20. The intake pressure sensor 8 detects the pressure (intake pressure) of the intake air flowing through the intake passage 32 and outputs a signal correlated with the detected pressure to the control unit 81. Thereby, the control unit 81 can detect the intake pressure.

  A cam position sensor 9 is provided in the vicinity of the cam shaft of the engine head 22. The cam position sensor 9 detects the rotational position of the camshaft that drives the exhaust valve 26 or the intake valve 25 to open and close, and outputs a signal correlated to the detected rotational position to the control unit 81. Thereby, the control unit 81 can detect the rotational position of the camshaft. Therefore, the control unit 81 can perform cam angle calculation, cylinder discrimination, and the like.

  The engine 20 is provided with a crank position sensor 14 in the vicinity of the crankshaft 29. The crank position sensor 14 detects the rotational position of the crankshaft 29 and outputs a signal correlated with the detected rotational position to the control unit 81. Thereby, the control unit 81 can detect the rotational position of the crankshaft 29. Therefore, the control unit 81 can calculate the crank angle and the rotation speed of the crankshaft 29, that is, the rotation speed of the engine 20.

  Further, the engine 20 is provided with a water temperature sensor 15 in the cylinder 21. The water temperature sensor 15 detects the temperature (water temperature) of the cooling water that cools the cylinder 21 and outputs a signal correlated to the detected temperature to the control unit 81. Thereby, the control unit 81 can detect the temperature of the cooling water.

  An A / F sensor 16 is provided between the engine 20 in the exhaust pipe 33 and the three-way catalyst 35. The A / F sensor 16 detects the air-fuel ratio in the engine 20 from the concentration of oxygen in the exhaust gas flowing through the exhaust passage 34 and the concentration of unburned gas, and outputs a signal correlated with the detected air-fuel ratio to the control unit 81. . Thereby, the control unit 81 can detect the air-fuel ratio in the engine 20.

An O ₂ sensor 17 is provided on the opposite side of the exhaust pipe 33 from the engine 20 with respect to the three-way catalyst 35. In the O ₂ sensor 17, the air-fuel ratio in the engine 20 is thicker than the stoichiometric air-fuel ratio from the electromotive force generated by the difference between the oxygen concentration in the atmosphere and the oxygen concentration in the exhaust gas flowing through the exhaust passage 34. Whether the state is (rich) or thin (lean) is detected, and a signal (rich signal or lean signal) corresponding to the detected state is output to the control unit 81. As a result, the control unit 81 can detect whether the air-fuel ratio in the engine 20 is richer or lighter than the stoichiometric air-fuel ratio.

The power supply 12 is provided with a voltage sensor 18. The voltage sensor 18 detects the voltage of the power supply 12 and outputs a signal correlated with the detected voltage to the control unit 81. Thereby, the control unit 81 can detect the voltage of the power supply 12.
The EGR valve device 5 outputs a signal correlated with the opening degree of the EGR valve in the EGR passage 37 to the control unit 81. Thereby, the control part 81 can detect the opening degree of an EGR valve.

  The control unit 81 operates the ignition device 11 including the ignition plug 40 and the ignition coil 50, the actuator 3 of the throttle valve 2, the fuel injection valve 4, the EGR valve device 5 and the like based on the signals from the various sensors described above. By controlling this, the operation of the engine 20 can be controlled.

  In this embodiment, the current detection circuit 91 is accommodated in the casing of the ignition circuit unit 13 (see FIG. 2). The ignition circuit unit 13 is provided with a resistor 92. The resistor 92 is provided such that one end is connected to the cathode side of the diode 54 of the ignition coil 50 and the other end is grounded. The current detection circuit 91 is provided so as to be connected between the diode 54 and the resistor 92. Thereby, the current detection circuit 91 can detect the current flowing from the diode 54 to the ground side, that is, the secondary current I2 flowing through the secondary coil 52.

  In this embodiment, the voltage detection circuit 95 is accommodated in the casing of the ignition circuit unit 13 (see FIG. 2). The ignition circuit unit 13 is provided with resistors 96 and 97. The resistor 96 is provided so that one end is connected between the secondary coil 52 and the spark plug 40. The resistor 97 is provided so that one end is connected to the other end of the resistor 96 and the other end is grounded. The voltage detection circuit 95 is provided so as to be connected between the resistor 96 and the resistor 97. Thereby, the voltage detection circuit 95 can detect the voltage between the secondary coil 52 and the spark plug 40, that is, the secondary voltage V <b> 2 that is a voltage generated in the secondary coil 52. Here, the voltage detection circuit 95 corresponds to “voltage detection means” in the claims.

Next, control of the ignition device 11 by the control unit 81 and ignition control of the air-fuel mixture in the combustion chamber 28 will be described.
The control unit 81 controls the igniter unit 60 so as to cut off the flow of current from the primary coil 51 to the ground side, thereby generating a high voltage in the secondary coil 52 and causing the ignition plug 40 to discharge. Control. Specifically, the control unit 81 controls the spark plug 40 by outputting the ignition signal IGt to the gate of the switching element 61 of the igniter unit 60. Here, the ignition signal IGt is a signal indicating off (Lo) or on (Hi). When the ignition signal IGt is off, the switching element 61 is turned off, and the flow of current (primary current I1) from the primary coil 51 to the ground side via the switching element 61 is interrupted. On the other hand, when the ignition signal IGt is on, the switching element 61 is turned on, and a current flow from the primary coil 51 to the ground side via the switching element 61 is allowed.

  When the ignition signal IGt changes from on to off, the flow of the primary current I1 flowing through the primary coil 51 is interrupted, and a high voltage is generated in the secondary coil 52. As a result, the spark plug 40 discharges between the center electrode 42 and the ground electrode 43 of the discharge part 41. As a result, the mixture in the combustion chamber 28 is ignited (ignited).

  In this way, the control unit 81 generates the ignition signal IGt and outputs the ignition signal IGt to the switching element 61 of the igniter unit 60 so that the ignition plug 40 is discharged at the timing when the ignition signal IGt falls from on to off. The plug 40 can be controlled. Here, the control unit 81 corresponds to “discharge control means” in the claims. The timing at which the ignition signal IGt falls from on to off is assumed to be when the control of the spark plug 40 by the “discharge control means” starts (the start of the control period).

  Further, the control unit 81 controls the energy input unit 70 so as to input electric energy to the ignition coil 50 after starting the control of the spark plug 40 by the “discharge control means”. Specifically, the control unit 81 controls the energy input unit 70 by controlling the switching element 73 by outputting the energy input period signal IGw to the driver circuit 78. Here, the energy input period signal IGw is a signal indicating OFF (Lo) or ON (Hi). The energy input period signal IGw is generated so as to rise from off to on after the ignition signal IGt falls from on to off, that is, after the control of the spark plug 40 by the “discharge control means” is started.

  The driver circuit 78 outputs the switching signal SWd to the gate of the switching element 73 while the energy input period signal IGw is on. Thereby, the switching element 73 performs a switching operation so that the energy input period signal IGw is in the on state or the off state during the on period.

  When the switching element 73 is in the on state, the electrical energy stored in the capacitor 76 is input to the ground side of the primary coil 51 of the ignition coil 50 via the switching element 73 and the diode 75. Here, the control unit 81 corresponds to “energy input control means” in the claims.

  When the energy input unit 70 is controlled by the “energy input control means” and electric energy is input to the ground side of the primary coil 51 of the ignition coil 50, an induced current is generated in the secondary coil 52 of the ignition coil 50. This induced current corresponds to electrical energy capable of maintaining the discharge state of the spark plug 40 generated by the control of the “discharge control means”. That is, it can be considered that “the energy input unit 70 inputs electric energy to the spark plug 40”.

  In the present embodiment, the “energy input control unit” feeds back the value of the secondary current I2 detected by the current detection circuit 91 so that the current corresponding to the current target value IGa that is a predetermined current value is secondary. For example, the energy input unit 70 is controlled by controlling the duty ratio of the switching signal SWd (ratio of the ON period to the switching period) so as to flow through the coil 52. Thus, during the period when the energy input unit 70 supplies electric energy to the ignition coil 50, the secondary current I2 that substantially corresponds to the current target value IGa flows through the secondary coil 52.

  The control unit 81 stores the electric energy in the capacitor 76 by controlling the switching element 72 via the driver circuit 77 before the electric energy is input to the ignition coil 50 by the “energy input control unit”. To do. Specifically, the driver circuit 77 outputs the switching signal SWc to the gate of the switching element 72 before the energy input period signal IGw is turned on, for example, during the period when the ignition signal IGt is on. Thereby, the switching element 72 performs a switching operation so as to be in an on state or an off state, for example, while the ignition signal IGt is on. As a result, electric energy is stored in the capacitor 76.

  In the present embodiment, the control unit 81 has “normal ignition control means” that controls ignition of the air-fuel mixture in the combustion chamber 28 only by controlling the spark plug 40 by “discharge control means”. In the ignition control of the air-fuel mixture by the “normal ignition control means”, electric energy is not input to the ignition coil 50 by the energy input unit 70, so that the discharge of the spark plug 40 is completed in a relatively short time. Therefore, the ignition control of the air-fuel mixture by the “normal ignition control means” is suitable in the case where the air-fuel mixture in the combustion chamber 28 is easily ignited (ignited).

  Further, the control unit 81 controls the ignition plug 40 by the “discharge control unit” and controls the ignition of the air-fuel mixture in the combustion chamber 28 by controlling the energy input unit 70 by the “energy input control unit”. It has “specific ignition control means”. In the ignition control of the air-fuel mixture by the “specific ignition control means”, electric energy is input to the ignition coil 50 by the energy input unit 70, so that the discharge of the spark plug 40 lasts for a relatively long time. Therefore, the ignition control of the air-fuel mixture by the “specific ignition control means” is suitable when the air-fuel mixture in the combustion chamber 28 is difficult to be ignited (ignited).

The control unit 81 determines the ease of ignition of the air-fuel mixture in the combustion chamber 28 according to, for example, the operating state of the engine 20 and the environmental conditions, and based on the determination result, the ignition control of the air-fuel mixture by the “normal control means” is performed. The air-fuel mixture ignition control by the “specific ignition control means” can be switched.
Next, estimation of the combustion state of the air-fuel mixture in the combustion chamber 28 by the control unit 81 will be described.

  In the present embodiment, the control unit 81 performs ignition by the “discharge control means” after “ignition control by the normal ignition control means” and after “ignition control by the specific ignition control means” in the combustion stroke of the engine 20. Based on the voltage value, which is a value corresponding to the voltage (secondary voltage V2) detected by the voltage detection circuit 95, controlling the plug 40 and controlling the energy input unit 70 by the “energy input control means”. The combustion state of the air-fuel mixture in the combustion chamber 28 is estimated. Here, the control unit 81 corresponds to “combustion state estimation means” in the claims.

  Specifically, the “combustion state estimating means” (the control unit 81) performs “after ignition control by the normal ignition control means” and after “ignition control by the specific ignition control means” in the combustion stroke of the engine 20. Based on the first voltage value Vd1, which is a value corresponding to the voltage (secondary voltage V2) detected by the voltage detection circuit 95 when the spark plug 40 is controlled by the “discharge control means”, the air-fuel mixture in the combustion chamber 28 The combustion pressure that is the pressure at the time of combustion is estimated. Further, the “combustion state estimating means” (control unit 81) is configured to perform “energy input control means” after “ignition control by the normal ignition control means” or “ignition control by the specific ignition control means” in the combustion stroke of the engine 20. Based on the second voltage value Vd2 that is a value corresponding to the voltage detected by the voltage detection circuit 95 when the energy input unit 70 is controlled by the above, the combustion speed that is the combustion speed of the air-fuel mixture in the combustion chamber 28 is estimated. .

More specifically, the “combustion state estimating means” estimates the combustion pressure based on the maximum absolute value of the first voltage value Vd1 when the spark plug 40 is controlled by the “discharge control means”. In addition, the “combustion state estimating means” is configured such that the maximum value of the absolute value of the second voltage value Vd2 when the energy input control unit 70 is controlled by the “energy input control means” and the slope of the second voltage value Vd2. Based on this, the combustion rate is estimated.
Then, the “combustion state estimation means” (control unit 81) estimates the combustion state of the air-fuel mixture in the combustion chamber 28 based on the estimated combustion pressure and combustion speed.

Next, an operation example of the control device 10 and the ignition device 11 controlled by the control device 10 will be described with reference to FIG. In this operation example, an example in which the control unit 81 performs “ignition control by the specific ignition control unit” is shown.
In the compression stroke of the engine 20, when the control unit 81 determines that energization of the primary coil 51 of the ignition coil 50 should be started at time t1, the ignition signal IGt is turned on. Thereby, energization (primary current I1) to primary coil 51 is started. In the present embodiment, the driver circuit 77 of the energy input unit 70 outputs the switching signal SWc that changes to ON or OFF to the switching element 72 during the period when the ignition signal IGt is ON (time t1 to 2). Therefore, the switching element 72 performs a switching operation so as to be in an on state or an off state while the ignition signal IGt is on. As a result, electric energy is accumulated in the capacitor 76.

  If it is determined that it is the timing when the control unit 81 should ignite the air-fuel mixture at time t2 (the timing when the control of the spark plug 40 should be started by the “discharge control means”), the ignition signal IGt is turned off. As a result, a secondary voltage V2 that is a negative voltage is generated in the secondary coil 52, the absolute value of the secondary voltage V2 becomes equal to or greater than a predetermined value at time t3, and the spark plug 40 is connected to the center electrode 42 of the discharge unit 41. And the ground electrode 43. As a result, the mixture in the combustion chamber 28 is ignited (ignited). At this time, the secondary current I2 in the negative direction flows through the secondary coil 52, and the absolute value of the secondary current I2 becomes a predetermined value or more. When the spark plug 40 is discharged at time t3, the absolute value of the secondary voltage V2 quickly becomes equal to or less than a predetermined value. The time after the time t3 (ignition timing) when the spark plug 40 is discharged and the air-fuel mixture is ignited corresponds to the combustion stroke of the engine 20.

  When the control unit 81 turns on the energy input period signal IGw at time t4 when the control of the spark plug 40 by the “discharge control means” ends, the driver circuit 78 of the energy input unit 70 switches the switching signal SWd to turn on or off. Is output to the switching element 73. Thereby, the input of electric energy from the energy input unit 70 to the ignition coil 50 is started. The switching element 73 performs a switching operation so that the energy input period signal IGw is in an on state or an off state during an on period (time t4 to 5). Therefore, electric energy is input from the energy input unit 70 to the ignition coil 50 during the period from time t4 to time t5. Thereby, the secondary current I2 having the same polarity as that of the secondary current I2 flowing through the secondary coil 52 when the spark plug 40 is discharged, that is, a negative secondary current I2 is superimposed. As a result, the discharge state of the spark plug 40 generated at time t3 is maintained.

  In the present embodiment, the “energy input control means” feeds back the value of the secondary current I2 detected by the current detection circuit 91, so that the current corresponding to the current target value IGa flows through the secondary coil 52. In order to control the charging unit 70, as shown in FIG. 3, during the period when the energy charging period signal IGw is on (time t4 to 5), the secondary coil 52 has a secondary current I2 that substantially corresponds to the current target value IGa. (Average value is IGa) flows.

When the control unit 81 turns off the energy input period signal IGw at time t5, the switching operation of the switching element 73 is stopped, and the input of electrical energy from the energy input unit 70 to the ignition coil 50 is stopped. Thereby, the discharge of the spark plug 40 is stopped at time t5, and the secondary current I2 and the secondary voltage V2 become zero.
In this way, the control unit 81 performs “ignition control by the specific ignition control means” during the period from time t2 to time t5.

  When the control unit 81 determines that energization of the primary coil 51 of the ignition coil 50 should be started at time t6 after a predetermined period has elapsed from time t5 when “ignition control by the specific ignition control means” ends, the ignition signal IGt is turned on. become. Thereby, energization (primary current I1) to primary coil 51 is started. The driver circuit 77 of the energy input unit 70 outputs the switching signal SWc that changes to ON or OFF to the switching element 72 during the period when the ignition signal IGt is ON (time t6-7). As a result, electric energy is accumulated in the capacitor 76.

  When the control unit 81 determines at the time t7 that it is time to start controlling the spark plug 40 by the “discharge control means”, the ignition signal IGt is turned off. As a result, a secondary voltage V2 that is a negative voltage is generated in the secondary coil 52, the absolute value of the secondary voltage V2 becomes equal to or greater than a predetermined value at time t8, and the spark plug 40 is connected to the center electrode 42 of the discharge unit 41. And the ground electrode 43.

  Here, in the present embodiment, the timing at which the control unit 81 should start controlling the spark plug 40 by the “discharge control means” is when the crank angle is displaced by a predetermined angle from the angle corresponding to the top dead center (TDC) ( It is set at time t7).

  The air-fuel mixture in the combustion chamber 28 starts combustion by “ignition control by the specific ignition control means” at time t2 to 5, and the crank angle is displaced by a predetermined angle from the angle corresponding to the top dead center (TDC), and time t7 At time t8 when the spark plug 40 starts discharging, combustion is in progress. Therefore, even if the spark plug 40 is discharged at time t8, ignition does not occur. That is, the discharge of the spark plug 40 at this time does not contribute to the ignition of the air-fuel mixture.

  As shown by a solid line in FIG. 5, when the combustion state of the air-fuel mixture in the combustion chamber 28 is “normal combustion”, when the crank angle is displaced by a predetermined angle from the angle corresponding to the top dead center (TDC), The combustion pressure that is the pressure at the time of combustion of the air-fuel mixture, that is, the pressure in the cylinder 21 (combustion chamber 28) (cylinder pressure) becomes a predetermined value or more. When the in-cylinder pressure is large, the absolute value of the secondary voltage V2 (break voltage) necessary for the spark plug 40 to start discharging increases.

  Therefore, as indicated by a solid line in FIG. 3, when the combustion state is “normal combustion”, the absolute value of the secondary voltage V2 when the spark plug 40 starts discharging at time t8 is determined by the “specific ignition control means”. It becomes larger than the absolute value of the secondary voltage V2 when the spark plug 40 starts discharging at the time of “discharge control” (time t3).

  On the other hand, as shown by a broken line in FIG. 5, when the combustion state of the air-fuel mixture in the combustion chamber 28 is “misfire”, when the crank angle is displaced by a predetermined angle from the angle corresponding to the top dead center (TDC), the in-cylinder pressure is , Smaller than in the “normal state”. Therefore, as shown by a broken line in FIG. 3, when the combustion state is “misfire”, the absolute value of the secondary voltage V2 (break voltage) when the spark plug 40 starts discharging at time t8 is “ It becomes smaller than the case of “normal combustion”.

  As shown by the one-dot chain line in FIG. 5, when the combustion state of the air-fuel mixture in the combustion chamber 28 is “slow combustion”, when the crank angle is displaced from the angle corresponding to the top dead center (TDC) by a predetermined angle, The internal pressure is smaller than in the “normal state” and larger than in the “misfire”.

  When the control unit 81 turns on the energy input period signal IGw at time t9 when the control of the spark plug 40 by the “discharge control means” ends, the driver circuit 78 of the energy input unit 70 switches the switching signal SWd to be turned on or off. Is output to the switching element 73. Thereby, the input of electric energy from the energy input unit 70 to the ignition coil 50 is started. The switching element 73 performs a switching operation so that the energy input period signal IGw is in the on state or the off state during the on period (time t9 to 11). Therefore, electric energy is input from the energy input unit 70 to the ignition coil 50 during the period from time t9 to time t11. Thereby, the discharge state of the spark plug 40 generated at time t8 is maintained.

  As shown by a solid line in FIG. 5, when the combustion state of the air-fuel mixture in the combustion chamber 28 is “normal combustion”, when the crank angle is displaced by a predetermined angle from the angle corresponding to the top dead center (TDC), The combustion speed, which is the combustion speed of the air-fuel mixture, is equal to or higher than a predetermined value. When the combustion rate in the combustion chamber 28 is high, the discharge path (electron path during discharge between the center electrode 42 and the ground electrode 43) when the spark plug 40 is discharged becomes long. At this time, the maximum absolute value of the secondary voltage V2 and the absolute value of the slope increase.

  Therefore, when the combustion state is “normal combustion”, the electrical discharge path when the electric energy is input from the energy input unit 70 to the ignition coil 50 and the discharge of the spark plug 40 is maintained (time t9 to 11) is: It becomes longer than the path when the discharge of the spark plug 40 is maintained (time t4-5) during the "energy input control" by the "specific ignition control means". Further, as indicated by a solid line in FIG. 3, when the combustion state is “normal combustion”, the absolute value of the secondary voltage V2 (discharge sustaining voltage) when the discharge of the spark plug 40 is maintained at time t9 to t11. And the absolute value of the slope of the secondary voltage V2 (discharge sustaining) when the discharge of the spark plug 40 is maintained (time t4-5) during the "energy input control" by the "specific ignition control means". The absolute value of the voltage) is larger than the absolute value of the absolute value and the absolute value of the slope.

  On the other hand, as shown by a broken line in FIG. 5, when the combustion state of the air-fuel mixture in the combustion chamber 28 is “misfire”, when the crank angle is displaced by a predetermined angle from the angle corresponding to the top dead center (TDC), The combustion speed of the air-fuel mixture at is lower than that in the “normal state”. Therefore, as indicated by a broken line in FIG. 3, when the combustion state is “misfire”, the absolute value of the secondary voltage V2 (discharge sustaining voltage) when the discharge of the spark plug 40 is maintained at time t9 to t11. The maximum value and the absolute value of the slope are smaller than when the combustion state is “normal combustion”.

  In the present embodiment, as shown in FIG. 4, the “combustion state estimation means” (control unit 81) performs “ignition control by specific ignition control means” (time t 2 to 5) in the combustion stroke of the engine 20. Combustion based on the first voltage value Vd1, which is a value corresponding to the voltage (secondary voltage V2) detected by the voltage detection circuit 95, when the spark plug 40 is controlled by the "discharge control means" (time t7-9). A combustion pressure that is a pressure at the time of combustion of the air-fuel mixture in the chamber 28 is estimated.

  Specifically, when the maximum value of the absolute value of the first voltage value Vd1 when the spark plug 40 is controlled by the “discharge control means” (time t7-9), the combustion pressure is estimated to be “large”. If the maximum value of the absolute value of the first voltage value Vd1 at this time is small, the combustion pressure is estimated to be “small”. For example, as shown by a solid line in FIG. 4, when the maximum absolute value of the first voltage value Vd1 at times t7 to t9 is large (| a4 |), the combustion pressure is estimated to be “large”. On the other hand, as shown by a broken line in FIG. 4, when the maximum absolute value of the first voltage value Vd1 at times t7 to t9 is small (| a3 |), the combustion pressure is estimated to be “small”.

  Further, as shown in FIG. 4, the “combustion state estimation means” (control unit 81) performs “energy input” after “ignition control by specific ignition control means” (time t 2 to 5) in the combustion stroke of the engine 20. Based on the second voltage value Vd2 that is a value corresponding to the voltage (secondary voltage V2) detected by the voltage detection circuit 95 when the energy input unit 70 is controlled by the “control means” (time t9 to 11). The combustion speed, which is the speed of combustion of the air-fuel mixture at 28, is estimated.

  Specifically, the maximum value of the absolute value of the second voltage value Vd2 when the energy input unit 70 is controlled by the “energy input control means” (time t9 to 11) is large, and the slope of the second voltage value Vd2 When the absolute value of the second voltage value Vd2 is large and the absolute value of the slope of the second voltage value Vd2 is small and the absolute value of the slope of the second voltage value Vd2 is small, the combustion speed is estimated. Is estimated to be “small”. For example, as indicated by a solid line in FIG. 4, the maximum absolute value of the second voltage value Vd2 at times t9 to t11 is large (| a2 |), and the absolute value of the slope of the second voltage value Vd2 is large (| ( a2-a1) / (t10-t9) |), it is estimated that the combustion speed is "high". On the other hand, as shown by a broken line in FIG. 4, the maximum absolute value of the second voltage value Vd2 at times t9 to t11 is small (| a1 |), and the absolute value of the slope of the second voltage value Vd2 is small (| ( a1-a1) / (t10-t9) |), the combustion rate is estimated to be “small”.

  The “combustion state estimation means” (control unit 81) controls the spark plug 40 by the “discharge control means” (time t7 to 9), and the energy input unit 70 by the “energy input control means”. Is controlled (time t9 to 11), based on the combustion pressure and combustion speed estimated during the estimation period, the combustion state of the air-fuel mixture in the combustion chamber 28 is estimated.

  Specifically, as shown in FIG. 6, since the maximum absolute value of the detected first voltage value Vd1 is large, the combustion pressure is estimated to be “large” and the maximum absolute value of the detected second voltage value Vd2 is estimated. When the value is large and the calculated absolute value of the slope of the second voltage value Vd2 is large, and it is estimated that the combustion speed is “high”, it is estimated that the combustion state of the air-fuel mixture in the combustion chamber 28 is “normal combustion”.

  On the other hand, since the detected absolute value of the first voltage value Vd1 is small, the combustion pressure is estimated to be “small”, and the detected absolute value of the second voltage value Vd2 is large, and the calculated second voltage value When it is estimated that the combustion speed is “small” because the absolute value of the slope of Vd2 is small, it is estimated that the combustion state of the air-fuel mixture in the combustion chamber 28 is “slow combustion or misfire”.

  In this embodiment, when the combustion state of the air-fuel mixture in the combustion chamber 28 is estimated by the “combustion state estimating means”, the “energy input control means” is the value of the secondary current I2 detected by the current detection circuit 91. , The energy input unit 70 is controlled so that the current corresponding to the current target value IGa flows through the secondary coil 52. Therefore, as shown in FIG. 3, the energy input period signal IGw is on (time t9). To 11), the secondary coil 52 flows a secondary current I2 (average value is IGa) substantially corresponding to the current target value IGa.

In the present embodiment, when the combustion state estimated by the “combustion state estimation unit” is “slow combustion or misfire”, the control unit 81 changes the current target value IGa to a value equal to or greater than a predetermined value. As a result, thereafter, the electric energy input to the ignition coil 50 during the “energy input control” when performing the “ignition control by the specific ignition control means” increases. As a result, the discharge state of the spark plug 40 can be maintained better, and the combustion state in the combustion chamber 28 can be brought close to “normal combustion”.
In the present embodiment, the combustion state estimation by the “combustion state estimation unit” is performed every time “ignition control by the normal ignition control unit” and “ignition control by the specific ignition control unit” are performed while the ignition key of the vehicle is on. I do.

  In addition, when the discharge part 41 of the spark plug 40 is consumed, the gap between the center electrode 42 and the ground electrode 43 increases. As the gap between the center electrode 42 and the ground electrode 43 increases, the absolute value of the secondary voltage V2 (break voltage) necessary for the spark plug 40 to start discharging increases. In the present embodiment, the control unit 81 has a first voltage value Vd1 that is a value corresponding to the voltage (secondary voltage V2) detected by the voltage detection circuit 95 when the spark plug 40 is controlled by the “discharge control means”. When the maximum absolute value of the spark plug 40 is equal to or greater than a predetermined value, an abnormality of the spark plug 40 is detected. When the control unit 81 detects an abnormality in the spark plug 40, for example, the control unit 81 stores the diagnosis information as diagnosis information, and lights a notification lamp or generates a notification sound on the display unit of the driver's seat of the vehicle. It is possible to notify the driver that “the abnormality is occurring in the ignition plug 40 of the ignition device 11”.

As described above, (1) In the present embodiment, the control unit 81 has “discharge control means”, “energy input control means”, “normal ignition control means”, and “specific ignition control means”, and combustion The ignition of the air-fuel mixture in the chamber 28 can be controlled.
The “discharge control means” generates a high voltage in the secondary coil 52 by controlling the igniter 60 so as to cut off the flow of current from the primary coil 51 to the ground side, so that the spark plug 40 is discharged. 40 is controlled. Thereby, the spark plug 40 is discharged, and the air-fuel mixture can be ignited.

The “energy input control unit” controls the energy input unit 70 to input electric energy to the ignition coil 50 after the control of the spark plug 40 by the “discharge control unit” is started. Thereby, the discharge state of the spark plug 40 caused by the control of the “discharge control means” can be maintained. Therefore, the ignitability of the air-fuel mixture can be improved.
The “normal ignition control means” controls the ignition of the air-fuel mixture in the combustion chamber 28 only by controlling the spark plug 40 by the “discharge control means”.

The “specific ignition control means” controls ignition of the air-fuel mixture in the combustion chamber 28 by controlling the spark plug 40 by “discharge control means” and controlling the energy input unit 70 by “energy input control means”. To do. When ignition control is performed by the “specific ignition control means”, the discharge state of the spark plug 40 can be maintained by the “energy input control means”, so that the ignitability of the air-fuel mixture can be improved.
The voltage detection circuit 95 can detect the voltage between the secondary coil 52 and the spark plug 40.

  In the combustion stroke of the engine 20, the control unit 81 ("combustion state estimation means") is an ignition plug by "discharge control means" after "ignition control by normal ignition control means" or "ignition control by specific ignition control means". 40 and the energy input unit 70 is controlled by the “energy input control means”, and a voltage value (first voltage) corresponding to the voltage (secondary voltage V2) detected by the voltage detection circuit 95 at this time is controlled. Based on the value Vd1 and the second voltage value Vd2), the combustion state of the air-fuel mixture in the combustion chamber 28 can be estimated.

  Thus, in this embodiment, in order to estimate the combustion state of the air-fuel mixture in the combustion chamber 28, it is not necessary to provide pressure detection means such as a pressure sensor in the combustion chamber 28, for example. Therefore, the combustion state can be estimated with a simple configuration, and the cost can be reduced. In addition, since it is not necessary to provide pressure detection means such as a pressure sensor in the combustion chamber 28, a situation such as “the combustion state cannot be estimated due to failure of the pressure detection means” is not caused.

  (2) In the present embodiment, the energy input unit 70 inputs electric energy to the ignition coil 50 from the ground side of the primary coil 51. The present embodiment shows an example of the configuration of the ignition device 11 (energy input unit 70). In the present embodiment, the ignition device 11 includes one ignition coil 50 for one ignition plug 40. The energy input unit 70 continuously supplies electric energy to the ignition coil 50 from the ground side of the primary coil 51, thereby maintaining the discharge state generated in the spark plug 40 for a predetermined period (energy input period). it can.

  (3) In the present embodiment, the control unit 81 (“combustion state estimation means”) performs “ignition control by the normal ignition control means” or “ignition control by the specific ignition control means” in the combustion stroke of the engine 20. Thereafter, the mixing in the combustion chamber 28 is performed based on the first voltage value Vd1 which is a value corresponding to the voltage (secondary voltage V2) detected by the voltage detection circuit 95 when the spark plug 40 is controlled by the “discharge control means”. Estimate the combustion pressure, which is the pressure at the time of combustion. In addition, the control unit 81 (“combustion state estimating means”) performs “energy input control means” after “ignition control by normal ignition control means” or “ignition control by specific ignition control means” in the combustion stroke of the engine 20. Based on the second voltage value Vd2 that is a value corresponding to the voltage (secondary voltage V2) detected by the voltage detection circuit 95 when the energy input unit 70 is controlled by the Estimate a certain burning rate. Then, the control unit 81 (“combustion state estimation means”) estimates the combustion state in the combustion chamber 28 based on the estimated combustion pressure and combustion speed. This specifically shows how to estimate the combustion state in the combustion chamber 28.

  (4) In the present embodiment, the control unit 81 (“combustion state estimating means”) is the maximum absolute value of the first voltage value Vd1 when the spark plug 40 is controlled by the “discharge control means”. Based on this, the combustion pressure is estimated. This specifically shows how to estimate the combustion pressure in the combustion chamber 28.

(5) In the present embodiment, the control unit 81 (“combustion state estimation means”) is the absolute value of the second voltage value Vd2 when the energy input unit 70 is controlled by the “energy input control means”. The combustion speed is estimated based on the maximum value and the absolute value of the slope of the second voltage value Vd2. This specifically shows how to estimate the combustion speed in the combustion chamber 28.
Thus, in the present embodiment, the combustion pressure and the combustion speed in the combustion chamber 28 are estimated based on the first voltage value Vd1 and the second voltage value Vd2. Therefore, the combustion state in the combustion chamber 28 can be estimated with high accuracy.

  (6) In the present embodiment, the “energy input control unit” controls the energy input unit 70 such that a current corresponding to the current target value IGa that is a predetermined current value flows through the secondary coil 52. Thus, during the period when the energy input unit 70 supplies electric energy to the ignition coil 50, the secondary current I2 that substantially corresponds to the current target value IGa flows through the secondary coil 52. As a result, the discharge state generated by the spark plug 40 can be stably maintained for a predetermined period (energy input period).

  Further, in this embodiment, when the combustion state of the air-fuel mixture in the combustion chamber 28 is estimated by the “combustion state estimation unit”, the “energy input control unit” is the value of the secondary current I2 detected by the current detection circuit 91. Since the energy input unit 70 is controlled so that a current corresponding to the current target value IGa flows through the secondary coil 52, the combustion speed in the combustion chamber 28 can be estimated with higher accuracy. Therefore, the combustion state in the combustion chamber 28 can be estimated with higher accuracy.

  (7) In the present embodiment, when the combustion state estimated by the “combustion state estimation means” is “slow combustion or misfire”, the control unit 81 changes the current target value IGa to a value equal to or greater than a predetermined value. To do. As a result, thereafter, the electric energy input to the ignition coil 50 during the “energy input control” when performing the “ignition control by the specific ignition control means” increases. As a result, the discharge state of the spark plug 40 can be maintained better, and the combustion state in the combustion chamber 28 can be brought close to “normal combustion”.

(Other embodiments)
In the above-described embodiment, an example in which the combustion state is estimated by the “combustion state estimation unit” after “ignition control by the specific ignition control unit” in the combustion stroke of the engine 20 has been described. On the other hand, in another embodiment of the present invention, in the combustion stroke of the engine 20, “combustion state” only after either “ignition control by normal ignition control means” or “ignition control by specific ignition control means”. The combustion state may be estimated by “estimating means”.

  (8) In another embodiment of the present invention, when the combustion state estimated by the “combustion state estimating means” is “slow combustion or misfire”, the control unit 81 sets the air-fuel ratio in the combustion chamber 28 to a predetermined value. The throttle valve 2 and the fuel injection valve 4 may be controlled so as to be equal to or less than the values. Thereby, thereafter, the air-fuel mixture in the combustion chamber 28 becomes in a state where it is easy to catch fire (ignition), and the combustion state in the combustion chamber 28 can be brought close to “normal combustion”.

  (9) In another embodiment of the present invention, when the combustion state estimated by the “combustion state estimating means” is “slow combustion or misfire”, the control unit 81 takes in the intake air supplied to the combustion chamber 28. It is also possible to control the throttle valve 2 so that the amount is less than a predetermined value. As a result, the vehicle can be retreated while reducing the rotational speed of the engine 20.

  Further, in the above-described embodiment, every time “ignition control by the normal ignition control means” or “ignition control by the specific ignition control means” is performed while the ignition key of the vehicle is on, the combustion state estimation means by the “combustion state estimation means” An example of estimation is given. On the other hand, (10) In another embodiment of the present invention, the “combustion state estimation means” may estimate the combustion state when the air-fuel ratio in the combustion chamber 28 is equal to or greater than a predetermined value. Thus, the combustion state is effectively estimated by limiting the estimation of the combustion state by the “combustion state estimating means” to “when the air-fuel ratio in the combustion chamber 28 is equal to or greater than a predetermined value”, which is likely to cause slow combustion or misfire. While estimating, consumption of electric energy by the energy input unit 70 accompanying combustion state estimation can be suppressed, and consumption of the discharge unit 41 of the spark plug 40 can be suppressed.

  (11) In another embodiment of the present invention, the “combustion state estimation means” estimates the combustion state when the EGR rate, which is the ratio of the exhaust gas recirculated to the combustion chamber 28 to the intake air, is greater than or equal to a predetermined value. It is good as well. Thus, by limiting the estimation of the combustion state by the “combustion state estimation means” to “when the EGR rate is equal to or higher than a predetermined value” where slow combustion or misfire is likely to occur, while effectively estimating the combustion state, It is possible to suppress the consumption of electric energy by the energy input unit 70 accompanying the estimation of the combustion state, and to suppress the consumption of the discharge unit 41 of the spark plug 40.

  (12) In another embodiment of the present invention, the “combustion state estimation means” may estimate the combustion state when the alcohol concentration of the fuel supplied to the combustion chamber 28 is equal to or higher than a predetermined value. In this case, for example, it is conceivable to include a concentration sensor that detects the alcohol concentration of the fuel and outputs a signal correlated with the detected alcohol concentration to the control unit 81. In this way, by limiting the estimation of the combustion state by the “combustion state estimation means” to “when the alcohol concentration of the fuel supplied to the combustion chamber 28 is equal to or higher than a predetermined value”, which is likely to cause slow combustion or misfire, for example, Even when flex fuel or the like, which is a mixed fuel of gasoline and alcohol, is used as the fuel to be supplied to the engine 20, the consumption of electric energy by the energy input unit 70 accompanying the estimation of the combustion state is reduced while effectively estimating the combustion state. It is possible to suppress the consumption of the discharge part 41 of the spark plug 40.

  Further, in the above-described embodiment, an example in which one ignition coil is provided for one ignition plug and the control device is applied to an ignition device in which the energy input unit inputs electric energy to the ignition coil from the ground side of the primary coil. Indicated. On the other hand, in another embodiment of the present invention, for example, a plurality of ignition coils are provided for one ignition plug, and electric energy is continuously input from the energy input unit to the plurality of ignition coils after discharge control of the ignition plug. Accordingly, the control device can be applied to an ignition device capable of maintaining the discharge state of the ignition plug.

  In the above-described embodiment, the “energy input control unit” feeds back the value of the secondary current I2, so that the current corresponding to the current target value IGa that is a predetermined current value flows through the secondary coil 52. The example which controls the energy input part 70 was shown. On the other hand, in another embodiment of the present invention, the “energy input control means” does not feed back the value of the secondary current I2, and the energy input so that the current corresponding to the current target value IGa flows through the secondary coil 52. The unit 70 may not be controlled.

In another embodiment of the present invention, when the combustion state estimated by the “combustion state estimation unit” is “slow combustion or misfire”, the control unit 81 sets the current target value IGa to a value equal to or greater than a predetermined value. It is good also as not changing.
In another embodiment of the present invention, the control unit 81 may not detect abnormality of the spark plug 40 based on the maximum absolute value of the first voltage value Vd1.

  Further, in another embodiment of the present invention, the energy input unit 70 may be configured without the capacitor 76. Even if the capacitor 76 is not provided, electric energy can be supplied to the ignition coil by appropriately switching the switching elements 72 and 73.

  In another embodiment of the present invention, the energy input unit may be, for example, a part that can input electric energy from a high-voltage power supply different from the power supply 12 to the ignition coil. In this case, compared with the above-mentioned embodiment, the number of members constituting the energy input unit can be reduced.

In another embodiment of the present invention, the switching element 61 of the igniter unit 60 is not limited to the IGBT, and may be configured by other semiconductor switching elements such as a MOSFET and a transistor. Further, since the MOSFET generally has a parasitic diode, the diode 62 can be omitted when the switching element 61 is configured by a MOSFET.
In another embodiment of the present invention, the switching elements 72 and 73 of the energy input unit 70 are not limited to MOSFETs, and may be configured by other semiconductor switching elements such as IGBTs and transistors.

Moreover, in the above-mentioned embodiment, the example which accommodates the igniter part 60 in the housing | casing of the ignition circuit unit 13 was shown. On the other hand, in another embodiment of the present invention, the igniter unit 60 may be provided in the vicinity of the ignition coil 50 without being housed in the casing of the ignition circuit unit 13.
In the above-described embodiment, the example in which the current detection circuit 91 and the voltage detection circuit 95 are housed in the casing of the ignition circuit unit 13 has been described. On the other hand, in another embodiment of the present invention, at least one of the current detection circuit 91 or the voltage detection circuit 95 may be housed in the casing of the ECU 80. The control unit 81 of the ECU 80 may include at least one of the current detection circuit 91 or the voltage detection circuit 95.
The control device of the present invention can also be applied to an ignition device for an engine system that does not include an exhaust gas recirculation (EGR) system.

In the above-described embodiment, an example in which a negative secondary current flows through the secondary coil of the ignition coil when the spark plug is discharged has been described. On the other hand, in another embodiment of the present invention, a secondary current in the positive direction may flow through the secondary coil of the ignition coil when the spark plug is discharged.
Moreover, in the above-mentioned embodiment, the energy injection | throwing-in part showed the example which inputs electric energy with respect to an ignition coil so that the secondary current of a negative direction may be superimposed. On the other hand, in another embodiment of the present invention, the energy input unit may be configured to input electric energy to the ignition coil such that a secondary current in the positive direction is superimposed.

Further, the control device of the present invention is not limited to a four-cylinder internal combustion engine, and can be applied to an ignition device for an internal combustion engine having a number of cylinders other than four.
The control device of the present invention is not limited to an internal combustion engine having one ignition coil and one ignition plug in each cylinder, but can also be applied to an ignition device for an internal combustion engine having a plurality of ignition coils or ignition plugs in each cylinder. .
The control device of the present invention is not limited to a premixed combustion type internal combustion engine, but can also be applied to an ignition device for a direct injection type internal combustion engine.
Thus, the present invention is not limited to the above-described embodiment, and can be implemented in various forms without departing from the gist thereof.

DESCRIPTION OF SYMBOLS 10 ... Control apparatus 11 ... Ignition apparatus 12 ... Power supply 20 ... Engine (internal combustion engine)
28 ... Combustion chamber 40 ... Spark plug 50 ... Ignition coil 51 ... Primary coil 52 ... Secondary coil 60 ... Igniter part 70 ... Energy input part 81 ... Control part (Discharge control means, energy input control means, normal ignition control means, specific ignition control means, combustion state estimation means)
95 ... Voltage detection circuit (voltage detection means)

Claims (12)

An ignition plug (40) provided in the combustion chamber (28) of the internal combustion engine (20) and capable of igniting an air-fuel mixture in the combustion chamber by discharging;
An ignition coil (50) having a primary coil (51) having one end connected to the power source (12) and the other end connected to the ground side, and a secondary coil (52) having one end connected to the spark plug; ,
An igniter section (60) provided to allow or block the flow of current from the primary coil to the ground side;
And a control device (10) capable of controlling an ignition device (11) including an energy input unit (70) capable of supplying electric energy to the ignition coil, and controlling ignition of an air-fuel mixture in the combustion chamber. ,
A discharge control means for controlling the ignition plug so as to cause the secondary coil to discharge by causing the secondary coil to generate a high voltage by controlling the igniter unit so as to cut off the flow of current from the primary coil to the ground side. (81),
After starting the control of the spark plug by the discharge control means, energy input control means (81) for controlling the energy input unit to input electric energy to the ignition coil;
Normal ignition control means (81) for controlling ignition of the air-fuel mixture in the combustion chamber only by controlling the spark plug by the discharge control means; and
Specific ignition control means (81) for controlling the ignition of the air-fuel mixture in the combustion chamber by controlling the spark plug by the discharge control means and controlling the energy input portion by the energy input control means. And
A control unit (81) capable of controlling ignition of the air-fuel mixture in the combustion chamber;
Voltage detection means (95) capable of detecting a voltage between the secondary coil and the spark plug;
In the combustion stroke of the internal combustion engine, after the “ignition control by the normal ignition control means” or “ignition control by the specific ignition control means”, the discharge control means controls the spark plug, and the energy input control The energy input unit is controlled by means, and the combustion state capable of estimating the combustion state of the air-fuel mixture in the combustion chamber based on voltage values (Vd1, Vd2) corresponding to the voltage detected by the voltage detecting means at this time State estimation means (81);
A control device comprising:   The control device according to claim 1, wherein the energy input unit inputs electric energy to the ignition coil from a ground side of the primary coil. The combustion state estimating means includes
In the combustion stroke of the internal combustion engine, after “ignition control by the normal ignition control means” or “ignition control by the specific ignition control means”,
Based on the first voltage value (Vd1), which is a value corresponding to the voltage detected by the voltage detecting means when the spark plug is controlled by the discharge control means, the pressure at the time of combustion of the air-fuel mixture in the combustion chamber Estimate a certain combustion pressure,
The speed of combustion of the air-fuel mixture in the combustion chamber based on the second voltage value (Vd2) that is a value corresponding to the voltage detected by the voltage detection means when the energy input control means is controlling the energy input control means. Estimate the burning rate,
The control device according to claim 1, wherein the combustion state is estimated based on the estimated combustion pressure and the combustion speed.   4. The combustion state estimating means estimates the combustion pressure based on a maximum absolute value of the first voltage value when the spark plug is controlled by the discharge control means. The control device described in 1.   The combustion state estimating means is based on the absolute value of the absolute value of the second voltage value and the absolute value of the slope of the second voltage value when the energy input control means is controlling the energy input unit. The control device according to claim 3, wherein the combustion speed is estimated.   The said energy input control means controls the said energy input part so that the electric current corresponding to the electric current target value (IGa) which is a predetermined electric current value may flow through the said secondary coil. A control device according to claim 1.   The said control part changes the said electric current target value to the value more than the said predetermined electric current value, when the said combustion state estimated by the said combustion state estimation means is slow combustion or misfire. The control device described in 1. The controller is
A throttle valve (2) capable of changing the amount of intake air supplied to the combustion chamber, and a fuel injection valve (4) capable of changing the amount of fuel supplied to the combustion chamber are controllable;
When the combustion state estimated by the combustion state estimation means is slow combustion or misfiring, the throttle valve and the fuel injection valve are controlled so that the air-fuel ratio in the combustion chamber becomes a predetermined value or less. The control apparatus as described in any one of Claims 1-7. The controller is
A throttle valve (2) capable of changing the amount of intake air supplied to the combustion chamber is controllable;
The throttle valve is controlled such that when the combustion state estimated by the combustion state estimation means is slow combustion or misfiring, the amount of intake air supplied to the combustion chamber becomes a predetermined value or less. Item 8. The control device according to any one of Items 1 to 7.   The control device according to any one of claims 1 to 9, wherein the combustion state estimation unit estimates the combustion state when an air-fuel ratio in the combustion chamber is a predetermined value or more.   The combustion state estimation means estimates the combustion state when an EGR rate, which is a ratio of exhaust gas recirculated to the combustion chamber, with respect to intake air is a predetermined value or more. The control device according to item.   The control according to any one of claims 1 to 11, wherein the combustion state estimation means estimates the combustion state when an alcohol concentration of fuel supplied to the combustion chamber is equal to or higher than a predetermined value. apparatus.

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